JP2007292931A - Developing device, image forming apparatus and process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device, an image forming apparatus and a process cartridge free from a defect, for example, apparent on an image caused by irregularity in a screw pitch even when the amount of a developer is small. <P>SOLUTION: The developing device includes a developer carrier, a regulating member which regulates the thickness of a developer on the developer carrier, a first stirring and conveying means 43Y and a second stirring and conveying means 44Y which convey the developer while stirring, wherein a developer surface height adjusting member 50Y which adjusts the height of the developer is disposed at a position upside the first stirring and conveying means 43Y and in contact with the developer carried and traveled on the developer carrier. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a developing device, an image forming apparatus, and a process cartridge, and more particularly to a developing device, an image forming apparatus, and a process cartridge that visualize an electrostatic latent image formed on an image carrier.

  2. Description of the Related Art Conventionally, a two-component developing method using a two-component developer composed of a nonmagnetic toner and a magnetic carrier has been widely used as a method for revealing an electrostatic latent image formed on an image carrier such as a photoreceptor. . A two-component developing device based on this method replenishes toner from a separately provided toner supply unit. The toner is agitated by the agitating means in the developing device and is carried on the developer carrier, and the electrostatic latent image on the image carrier is visualized using this developer.

  The toner from the toner supply unit is sufficiently agitated by the agitating means and then carried on the developer carrier while being conveyed. However, if the amount of the developer is too small, the height of the agent surface becomes low, and the developer carrier There is a problem that the supply to the ink is insufficient and unevenness of the stirring and conveying means, that is, the screw pitch appears in the image. In order to prevent this, it is necessary to increase the amount of the developer and increase the height of the agent surface. Therefore, in recent years, it has become the mainstream to provide a large developer storage space in the developing device and store the developer in the developing device in advance. It is difficult to secure the developer amount.

In the case of a developer container that transports developer in the axial direction of the screw by two screws, the replenished toner is transported so as to slide on the top of the developer, and the replenished toner and the developer are sufficiently mixed.・ There was a problem that stirring was difficult. In order to solve this problem, there has been proposed a developing device in which a toner guide for guiding the replenished toner to the developer upstream in the rotation direction of the conveying screw in the developer container is provided in the vicinity of the toner replenishing port of the developer container. (For example, refer to Patent Document 1).
JP 2004-69789 A

  However, since the apparatus provided with the toner guide is configured to supply toner into the developer, there arises a problem that the amount of toner taken in varies depending on the height (pressure) of the surface of the agent. Further, the space on the developer carrying member and the conveying screw portion cannot sufficiently maintain the height of the agent surface, and there is a concern that screw pitch unevenness is likely to occur.

  The present invention has been made in view of such a situation, and the amount of developer is reduced when the toner from the toner supply unit is carried on the developer carrying member while being agitated and conveyed by the agitating and conveying means. Even if the developing device and the image forming apparatus are capable of forming a highly reliable image without defects such as screw pitch unevenness appearing in the image due to insufficient supply of the developer to the developer carrying member. And it aims at providing a process cartridge.

  According to the first aspect of the present invention, there is provided a developer carrier, a regulating member that regulates the thickness of the developer on the developer carrier, a first stirring / conveying means for conveying the developer while stirring, and a second A developing device having an agitating / conveying means, wherein the height of the developer is above the first agitating / conveying means and at a position in contact with the developer carried and moved on the developer carrying member; And a developer surface height adjusting member for adjusting the developer.

  According to a second aspect of the present invention, in the apparatus according to the first aspect, the developer surface height adjusting member has an L-shaped cross-section, and the upstream side of the first agitating and conveying means is the downstream side. The height is reduced for a while.

  According to a third aspect of the present invention, in the apparatus according to the first or second aspect, the developer is a two-component developer including a toner and a magnetic carrier, and the particle size of the magnetic carrier is 20 to 50 μm. It is characterized by.

  According to a fourth aspect of the present invention, in the apparatus according to the third aspect, in the magnetic carrier, a resin-coated film is coated on a magnetic core material, and the resin-coated film crosslinks a thermoplastic resin and a melamine resin. The resin component and the charge control agent are contained.

  According to a fifth aspect of the present invention, in the apparatus according to the third or fourth aspect, the toner contains at least a polyester prepolymer having a functional group containing a nitrogen atom, a polyester, a colorant, and a release agent in an organic solvent. It is a toner obtained by subjecting the toner material liquid dispersed in the toner to at least one of a crosslinking reaction or an elongation reaction in an aqueous medium.

  According to a sixth aspect of the present invention, in the apparatus according to the fifth aspect, the toner has a volume average particle diameter of 3 to 8 μm, and a ratio of the volume average particle diameter (Dv) to the number average particle diameter (Dn) ( Dv / Dn) is in the range of 1.00 to 1.40.

  According to a seventh aspect of the present invention, in the apparatus according to the fifth or sixth aspect, the toner has a shape factor SF-1 in the range of 100 to 180 and a shape factor SF-2 in the range of 100 to 180. It is characterized by that.

  According to an eighth aspect of the present invention, in the apparatus according to any one of the fifth to seventh aspects, the toner has a substantially spherical shape, and the shape is defined by a major axis r1, a minor axis r2, and a thickness r3. (Where r1 ≧ r2 ≧ r3), the ratio of the major axis r1 to the minor axis r2 (r2 / r1) is in the range of 0.5 to 1.0, and the thickness r3 and minor axis r2 The ratio (r3 / r2) is in the range of 0.7 to 1.0.

  According to a ninth aspect of the present invention, there is provided an image carrier, a charging unit for charging the image carrier, a transfer unit for transferring a toner image to a transfer material, and a transfer residual toner remaining on the image carrier after the transfer. And a developing device that carries the developer on the developer carrying member and transports the developer to a developing region facing the image carrying member to develop the latent image on the image carrying member into a toner image. An image forming apparatus comprising: the developing device according to claim 1, wherein the developing device is the developing device according to claim 1.

  According to a tenth aspect of the present invention, the latent image on the image carrier is developed by carrying the image carrier and at least a developer on the developer carrier and transporting the developer to a development area facing the image carrier. 9. A process cartridge that integrally supports a developing device that forms a toner image and is detachably attached to an image forming apparatus main body, wherein the developing device is a developing device according to any one of claims 1 to 8. A process cartridge characterized by being an apparatus.

  According to the present invention, since the developer is at least agitated by the developer, the height of the agent surface can be adjusted, and defects such as screw pitch unevenness do not appear in the image. High image quality can be formed.

  Hereinafter, a developing device, an image forming apparatus, and a process cartridge according to an embodiment of the present invention will be described in detail with reference to the drawings. The embodiments described below are preferred embodiments of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention is particularly limited in the following description. As long as there is no description which limits, it is not restricted to these aspects.

  As an example of an image forming apparatus according to an embodiment of the present invention, a color laser printer (hereinafter referred to as “laser printer”) using an electrophotographic direct transfer method will be described.

  FIG. 1 is a schematic configuration diagram of a laser printer according to the present embodiment. This laser printer includes four toner image forming units 1Y, 1M, 1C, 1K (hereinafter referred to as “yellow” (Y), magenta (M), cyan (C), and black (K)). The subscripts Y, M, C, and K of the respective symbols indicate yellow, magenta, cyan, and black members, respectively. The moving direction of the transfer paper 100 (the belt 60 along the arrow A in the figure). In the traveling direction) from the upstream side.

  Each of the toner image forming units 1Y, 1M, 1C, and 1K includes photosensitive drums 11Y, 11M, 11C, and 11K as image carriers and a developing unit. Further, the arrangement of the toner image forming units 1Y, 1M, 1C, and 1K is set so that the rotation axes of the photosensitive drums are parallel to each other and arranged at a predetermined pitch in the transfer paper moving direction. Yes.

  This laser printer carries the toner image forming units 1Y, 1M, 1C, and 1K as well as the optical writing unit 2, the paper feed cassettes 3, 4, the registration roller pair 5, and the transfer paper 100, and each toner image forming unit. A transfer unit 6 as a belt driving device having a transfer conveyance belt 60 as a transfer conveyance member that conveys the sheet so as to pass through the transfer position, a belt fixing type fixing unit 7, a paper discharge tray 8, and the like. In addition, a manual feed tray MF and a toner supply container TC are provided, and a waste toner bottle, a duplex / reversing unit, a power supply unit, and the like (not shown) are also provided in a space S indicated by a two-dot chain line.

  The optical writing unit 2 includes a light source, a polygon mirror, an f-θ lens, a reflection mirror, and the like, and irradiates the surface of each of the photosensitive drums 11Y, 11M, 11C, and 11K while scanning the laser beam based on the image data. To do.

  A one-dot chain line in FIG. 1 indicates a conveyance path of the transfer paper 100. The transfer paper 100 fed from the paper feed cassettes 3 and 4 or the manual feed tray MF is transported by transport rollers while being guided by a transport guide (not shown), and is transported to a temporary stop position where the registration roller pair 5 is provided. The transfer paper 100 delivered at a predetermined timing by the registration roller pair 5 is carried on the transfer conveyance belt 60, conveyed toward the toner image forming units 1Y, 1M, 1C, and 1K, and passes through the transfer nips. .

  The toner images developed on the toner drums 11Y, 11M, 11C, and 11K of the toner image forming units 1Y, 1M, 1C, and 1K are superimposed on the transfer paper 100 at the transfer nips, respectively. It is transferred onto the transfer paper 100 under the action of pressure. By this superposition transfer, a full-color toner image is formed on the transfer paper 100. The surfaces of the photosensitive drums 11Y, 11M, 11C, and 11K after the toner image transfer are cleaned by a cleaning device, and are further discharged to prepare for the formation of the next electrostatic latent image.

  On the other hand, the transfer paper 100 on which the full-color toner image is formed is fixed in the first discharge direction B or the second in accordance with the rotation posture of the switching guide G after the full-color toner image is fixed by the fixing unit 7. In the paper discharge direction C. When the paper is discharged from the first paper discharge direction B onto the paper discharge tray 8, it is stacked in a so-called face-down state with the image surface down. On the other hand, when the paper is discharged in the second paper discharge direction C, it is conveyed toward another post-processing device (such as a sorter or a binding device) (not shown), or registered again for double-sided printing via a switchback unit. It is conveyed to the roller pair 5.

  In the casing, a two-component developer 49Y including a magnetic carrier and a negatively chargeable Y toner is accommodated (see FIG. 2). In the following description, the yellow (Y) image forming unit will be described as an example, but the same applies to other colors. The two-component developer 49Y is frictionally charged while being agitated and conveyed by the first conveying screw 43Y and the second conveying screw 44Y, and then carried on the surface of the developing roller 42Y.

  Then, after the layer thickness is regulated by the regulating blade 45Y, the layer is conveyed to the developing area facing the photoreceptor 2Y, where Y toner is attached to the electrostatic latent image on the photoreceptor 2Y. This adhesion forms a Y toner image on the photoreceptor 2Y. The two-component developer that has consumed Y toner by development is returned to the casing as the developing roller 42Y rotates.

  A partition wall 47Y is provided between the first conveying screw 43Y and the second conveying screw 44Y. The partition wall 47Y separates the first supply unit that accommodates the developing roller 42Y, the first conveyance screw 43Y, and the like and the second supply unit that accommodates the second conveyance screw 44Y in the casing. The first conveying screw 43Y is rotationally driven by a driving means (not shown), and is supplied to the developing roller 42Y while conveying the two-component developer in the first supply unit from the front side to the back side in the drawing.

  The two-component developer conveyed to the vicinity of the end of the first supply unit by the first conveyance screw 43Y enters the second supply unit through an opening (not shown) provided in the partition wall 47Y. In the second supply unit, the second conveyance screw 44Y is driven to rotate by a driving unit (not shown), and conveys the two-component developer sent from the first supply unit in a direction opposite to that of the first conveyance screw 43Y. . The two-component developer conveyed to the vicinity of the end of the second supply unit by the second conveyance screw 44Y returns to the first supply unit through the other opening (not shown) provided in the partition wall 47Y. .

  The T sensor 46Y for detecting the toner density composed of a magnetic permeability sensor is provided on the bottom wall near the center of the second supply unit, and has a voltage corresponding to the magnetic permeability of the two-component developer passing thereover. Is output. Since the magnetic permeability of the two-component developer has a certain degree of correlation with the toner density, the T sensor 46Y outputs a voltage having a value corresponding to the Y toner density. This output voltage value is sent to a control unit (not shown). This control unit includes a RAM, in which Y Vtref, which is a target value of the output voltage from the T sensor 46Y, is stored.

  In addition, data of M Vtref, C Vtref, and K Vtref, which are target values of output voltage from a T sensor (not shown) mounted in another developing device, is also stored. The Y Vtref is used for driving control of a Y toner conveying device (not shown). Specifically, the control unit drives and controls a Y toner conveying device (not shown) so that the value of the output voltage from the T sensor 46Y approaches the V Vref for Y, and supplies Y toner into the second supply unit 49Y. Replenish. By this replenishment, the Y toner concentration of the two-component developer in the developing device 40Y is maintained within a predetermined range. The same toner replenishment control is performed for the developing devices of other process cartridges.

  Next, the developing device according to the embodiment of the present invention will be described. FIG. 3 shows a developing device according to an embodiment of the present invention at a position in contact with the developer moving on the developer carrier on the upper side of the first agitating and conveying means (or the first conveying screw) 43Y. FIG. 10 is a view provided with a developer surface height adjusting member 50Y for increasing the height of the developer surface on the upper side of the first stirring and conveying means. In the state without the developer surface height adjusting member 50Y, the first conveying screw 43Y, the upper surface of the developer, and the sleeve surface of the developer carrier 42Y are close to each other, so the amount of developer carried and moved on the developer carrier. However, it is affected by the portion where the screw of the first conveying screw 43Y is present and the portion where the screw is not present, resulting in unevenness of the developer layer thickness on the developer carrier.

  However, as shown in FIG. 3, since the agent surface itself is raised by providing the agent surface height adjusting member 50Y for increasing the height of the developer surface above the first conveying screw, it is less susceptible to the influence of the screw. Become. Further, even if the screw is affected by the screw, the developer carried on the developer carrying member is in contact with the developer surface height adjusting member at the closest portion 50aY of the agent level adjusting member with the developer carrying member. Thus, the developer layer thickness unevenness (screw pitch unevenness) can be leveled (uniformized) by the agent surface height adjusting member 50Y.

  The developer surface height adjusting member 50Y is attached to the partition wall 47Y of the developing case by a fixing means such as a double-sided tape or an adhesive (including a pressure sensitive adhesive). Accordingly, it is possible to arbitrarily select a shape that optimally adjusts the gap at the closest part of the developer surface height adjusting member to the developer carrying member according to the amount of the developer.

  FIG. 4A is a top view of the agitating unit of the developing unit according to the embodiment of the present invention. The flow of the developer is indicated by a thick arrow. The toner replenished from the right side of the second conveying screw 44Y moves to the left in the drawing while being agitated together with the developer by the second conveying screw 44Y. And it moves to the 1st conveyance screw 43Y side at the left end, and this time it moves from the drawing left to the right side by the 1st conveyance screw 43Y. At 55Y, the developer flows back from the first conveying screw to the second conveying screw.

  FIG. 4B shows the height of the developer surface at that time. FIG. 4B shows a view from the A direction of FIG. Since the reflux rate of the developer is slow at the developer delivery portion, the developer is high on the left side of the drawing on the second conveying screw side, while the right side of the drawing is high on the first conveying screw side. As shown in FIG. 4B, the developer surface height is low on the left side and high on the right side, and the left side is far from the developer carrier 42Y, which is disadvantageous for screw pitch unevenness. .

  As shown in FIG. 4C, the developer surface height adjusting member 50Y is configured so that the cross-sectional shape of the developer surface height adjusting member 50Y decreases for a while depending on the height of the agent surface, thereby applying extra stress to the developer. At the same time, it is possible to prevent the occurrence of screw pitch unevenness.

  According to the above embodiment, the developer surface height adjusting member is provided at a position in contact with the developer moving on the developer carrier, so that the developer is not pumped up by the agitating and conveying means (pitch unevenness). To provide a highly reliable developing device in which development pitch unevenness images do not occur due to the effect of smoothing the developer surface height adjusting member and the stirring of the developer at the location where the agent surface height adjusting member is disposed. Can do.

  Further, the cross-sectional shape of the developer surface height adjusting member 50Y is, for example, an inverted L-shape as shown in FIG. 4C, and the upstream side of the first agitating and conveying means increases greatly toward the downstream side. By reducing the sectional shape for a while, it is possible to eliminate the difference in the stress applied to the developer in the longitudinal direction, and to provide a highly reliable developing device that does not impair the life of the developer and does not cause development pitch unevenness images. be able to.

  In addition, when the developer used in the developing device is a two-component developer composed of toner and magnetic particles, it is possible to form an image with more excellent dot reproducibility by reducing the carrier particle size. . Specifically, the carrier particle size is desirably 20 μm or more and 50 μm or less.

  In addition, by setting the carrier particle size smaller than before and further setting the particle size in such a range, it becomes possible to uniformly reduce the thickness of the developer spike (carrier chain) at the time of image formation, More precise toner can be delivered. In addition, since the density of developer spikes per single area on the developing sleeve increases, toner can be transferred to the latent image on the photoreceptor without gaps, and an image with better dot reproducibility can be formed. Can do.

  When the carrier particle size is too larger than 50 μm, the total surface area of the carrier becomes small when compared with the same carrier amount, and the amount of toner held decreases. For this reason, the toner density is lowered. Although it is possible to increase the pumping amount to maintain the developing ability, toner sticking is likely to occur. On the other hand, if the carrier particle size is smaller than 20 μm, the magnetic force holding force by the mag roller is reduced, causing carrier scattering and increasing carrier adhesion to the photosensitive member. However, when the dot reproducibility becomes high (high image quality), development unevenness and the like become conspicuous. However, according to the above-described embodiment, it is possible not only to provide an image having excellent dot reproducibility by reducing the particle size of the carrier, but also to provide a developing device with little development unevenness.

  Further, as the magnetic particles, a magnetic core material is coated with a resin coat film, and the resin coat film contains a resin component obtained by crosslinking a thermoplastic resin and a melamine resin, and a charge control agent. It is preferable to use it. Specifically, it is desirable to use a coat film having elasticity and strong adhesive force, which is coated with a coat film containing particles having a diameter larger than the film thickness on the surface.

  FIG. 5 is an explanatory diagram of carriers as magnetic particles according to the embodiment of the present invention. Ferrite 501 is used as the core material of the carrier 500. The surface of the ferrite 501 is coated with a coating film 502 containing a charge adjusting agent in a resin component obtained by crosslinking a thermoplastic resin such as acrylic and a melamine resin. The coat film 502 has elasticity and strong adhesive force. Further, particles having a diameter larger than the film thickness of the coat film 502, for example, alumina particles 503 are dispersed on the surface. The alumina particles 503 are held with a strong adhesive force of the coating film 502.

  The conventional carrier is configured based on the idea of obtaining a long life while gradually scraping off the hard coat film, whereas the carrier 500 according to the present embodiment shown in the figure has an impact due to the elasticity of the coat film 502. Film absorption can be effectively suppressed. Further, by dispersing alumina particles 503 having a diameter larger than the film thickness on the surface of the carrier 501, the impact on the coating film 502 can be prevented and the spent material can be cleaned.

  As described above, since the coating film can be prevented from being scraped and spent, it is possible to achieve a longer life than conventional carriers. Thereby, it is possible to expect stabilization of the amount of developer to be pumped over a long period of time, that is, stabilization of quality. In addition, by extending the service life, not only user maintenance is reduced, but also the manufacturing manufacturer is advantageous in terms of cost, and it can be said that it is friendly to the global environment from the viewpoint of the resource environment.

  Next, the toner of the developer that is preferably used in the developing device according to the embodiment of the present invention will be described. The toner used in the exemplary embodiment includes a toner material liquid in which at least a polyester prepolymer having a functional group containing a nitrogen atom, polyester, a colorant, and a release agent is dispersed in an organic solvent in an aqueous solvent. A toner obtained by crosslinking and / or elongation reaction is preferred.

The constituent material and manufacturing method of such toner will be described below.
(polyester)
The polyester is obtained by a polycondensation reaction between a polyhydric alcohol compound and a polycarboxylic acid compound. Examples of the polyhydric alcohol compound (PO) include dihydric alcohol (DIO) and trihydric or higher polyhydric alcohol (TO). (DIO) alone or a mixture of (DIO) and a small amount of (TO) preferable.

  Examples of the dihydric alcohol (DIO) include alkylene glycol (ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, etc.); alkylene ether glycol (diethylene glycol) , Triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, etc.); alicyclic diols (1,4-cyclohexanedimethanol, hydrogenated bisphenol A, etc.); bisphenols (bisphenol A, bisphenol) F, bisphenol S, etc.); alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, etc.) adduct of the above alicyclic diol; Alkylene oxide bisphenol (ethylene oxide, propylene oxide, butylene oxide, etc.), etc. adducts.

  Among them, preferred are alkylene glycols having 2 to 12 carbon atoms and alkylene oxide adducts of bisphenols, and particularly preferred are alkylene oxide adducts of bisphenols and alkylene glycols having 2 to 12 carbon atoms. It is a combined use.

  The trihydric or higher polyhydric alcohol (TO) includes 3 to 8 or higher polyhydric aliphatic alcohols (glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, sorbitol, etc.); trihydric or higher phenols (Trisphenol PA, phenol novolak, cresol novolak, etc.); and alkylene oxide adducts of the above trivalent or higher polyphenols.

  Examples of the polyvalent carboxylic acid (PC) include divalent carboxylic acid (DIC) and trivalent or higher polyvalent carboxylic acid (TC). (DIC) alone and (DIC) with a small amount of (TC) Mixtures are preferred. Divalent carboxylic acids (DIC) include alkylene dicarboxylic acids (succinic acid, adipic acid, sebacic acid, etc.); alkenylene dicarboxylic acids (maleic acid, fumaric acid, etc.); aromatic dicarboxylic acids (phthalic acid, isophthalic acid, terephthalic acid) And naphthalenedicarboxylic acid).

  Of these, preferred are alkenylene dicarboxylic acids having 4 to 20 carbon atoms and aromatic dicarboxylic acids having 8 to 20 carbon atoms. Examples of the trivalent or higher polyvalent carboxylic acid (TC) include aromatic polycarboxylic acids having 9 to 20 carbon atoms (such as trimellitic acid and pyromellitic acid). In addition, as polyhydric carboxylic acid (PC), you may make it react with polyhydric alcohol (PO) using the above-mentioned acid anhydride or lower alkyl ester (Methyl ester, ethyl ester, isopropyl ester, etc.).

  The ratio of the polyhydric alcohol (PO) to the polycarboxylic acid (PC) is usually 2/1 to 1/1, preferably as the equivalent ratio [OH] / [COOH] of the hydroxyl group [OH] and the carboxyl group [COOH]. Is 1.5 / 1 to 1/1, more preferably 1.3 / 1 to 1.02 / 1.

  The polycondensation reaction between a polyhydric alcohol (PO) and a polycarboxylic acid (PC) is carried out in the presence of a known esterification catalyst such as tetrabutoxytitanate or dibutyltin oxide, and heated to 150 to 280 ° C. while reducing the pressure as necessary. The produced water is distilled off to obtain a polyester having a hydroxyl group. The hydroxyl value of the polyester is preferably 5 or more, and the acid value of the polyester is usually 1 to 30, preferably 5 to 20. By giving an acid value, the toner tends to be negatively charged, and further, when fixing to a recording paper, the affinity between the recording paper and the toner is good and the low-temperature fixability is improved. However, when the acid value exceeds 30, there is a tendency to deteriorate with respect to the stability of charging, particularly environmental fluctuation. The weight average molecular weight is 10,000 to 400,000, preferably 20,000 to 200,000. A weight average molecular weight of less than 10,000 is not preferable because offset resistance deteriorates. On the other hand, if it exceeds 400,000, the low-temperature fixability is deteriorated.

  In addition to the unmodified polyester obtained by the above polycondensation reaction, the polyester preferably contains a urea-modified polyester. The urea-modified polyester is obtained by reacting a terminal carboxyl group or hydroxyl group of the polyester obtained by the above polycondensation reaction with a polyvalent isocyanate compound (PIC) to obtain a polyester prepolymer (A) having an isocyanate group. It is obtained by cross-linking and / or extending the molecular chain by the reaction of the amine with amines.

  Examples of the polyvalent isocyanate compound (PIC) include aliphatic polyisocyanates (tetramethylene diisocyanate, hexamethylene diisocyanate, 2,6-diisocyanatomethylcaproate, etc.); alicyclic polyisocyanates (isophorone diisocyanate, cyclohexylmethane diisocyanate, etc.) Aromatic diisocyanates (tolylene diisocyanate, diphenylmethane diisocyanate, etc.); araliphatic diisocyanates (α, α, α ′, α′-tetramethylxylylene diisocyanate, etc.); isocyanates; Those blocked with caprolactam or the like; and combinations of two or more of these.

  The ratio of the polyvalent isocyanate compound (PIC) is usually 5/1 to 1/1, preferably as an equivalent ratio [NCO] / [OH] of the isocyanate group [NCO] and the hydroxyl group [OH] of the polyester having a hydroxyl group. 4/1 to 1.2 / 1, more preferably 2.5 / 1 to 1.5 / 1. When [NCO] / [OH] exceeds 5, low-temperature fixability deteriorates. When the molar ratio of [NCO] is less than 1, when a urea-modified polyester is used, the urea content in the ester is lowered and hot offset resistance is deteriorated.

  The content of the polyvalent isocyanate compound (PIC) component in the polyester prepolymer (A) having an isocyanate group is usually 0.5 to 40 wt%, preferably 1 to 30 wt%, more preferably 2 to 20 wt%. . If it is less than 0.5 wt%, the hot offset resistance deteriorates, and it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability. On the other hand, if it exceeds 40 wt%, the low-temperature fixability deteriorates.

  The number of isocyanate groups contained per molecule in the polyester prepolymer (A) having an isocyanate group is usually 1 or more, preferably 1.5 to 3 on average, more preferably 1.8 to 2 on average. Five. If it is less than 1 per molecule, the molecular weight of the urea-modified polyester will be low, and the hot offset resistance will deteriorate.

  Next, as amines (B) to be reacted with the polyester prepolymer (A), a divalent amine compound (B1), a trivalent or higher polyvalent amine compound (B2), an amino alcohol (B3), an amino mercaptan (B4) ), Amino acid (B5), and amino acid block of B1 to B5 (B6).

  Examples of the divalent amine compound (B1) include aromatic diamines (phenylenediamine, diethyltoluenediamine, 4,4′-diaminodiphenylmethane, etc.); alicyclic diamines (4,4′-diamino-3,3′-dimethyldicyclohexyl). Methane, diamine cyclohexane, isophorone diamine, etc.); and aliphatic diamines (ethylene diamine, tetramethylene diamine, hexamethylene diamine, etc.) and the like.

  Examples of the trivalent or higher polyvalent amine compound (B2) include diethylenetriamine and triethylenetetramine. Examples of amino alcohol (B3) include ethanolamine and hydroxyethylaniline.

  Examples of amino mercaptan (B4) include aminoethyl mercaptan and aminopropyl mercaptan. Examples of the amino acid (B5) include aminopropionic acid and aminocaproic acid. Examples of the compound (B6) obtained by blocking the amino group of B1 to B5 include ketimine compounds and oxazolidine compounds obtained from the amines of B1 to B5 and ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.). Among these amines (B), preferred are B1 and a mixture of B1 and a small amount of B2.

  The ratio of amines (B) is equivalent to the equivalent ratio [NCO] / [NHx] of isocyanate groups [NCO] in the polyester prepolymer (A) having isocyanate groups and amino groups [NHx] in amines (B). Is usually 1/2 to 2/1, preferably 1.5 / 1 to 1 / 1.5, more preferably 1.2 / 1 to 1 / 1.2. When [NCO] / [NHx] exceeds 2 or less than 1/2, the molecular weight of the urea-modified polyester is lowered, and the hot offset resistance is deteriorated.

  The urea-modified polyester may contain a urethane bond together with a urea bond. The molar ratio of the urea bond content to the urethane bond content is usually 100/0 to 10/90, preferably 80/20 to 20/80, and more preferably 60/40 to 30/70. When the molar ratio of the urea bond is less than 10%, the hot offset resistance is deteriorated.

  The urea-modified polyester is produced by a one-shot method or the like. Polyhydric alcohol (PO) and polyvalent carboxylic acid (PC) are heated to 150-280 ° C. in the presence of a known esterification catalyst such as tetrabutoxytitanate, dibutyltin oxide, etc., and water generated while reducing the pressure as necessary. Distill off to obtain a polyester having a hydroxyl group. Subsequently, at 40-140 degreeC, this is made to react with polyvalent isocyanate (PIC), and the polyester prepolymer (A) which has an isocyanate group is obtained. Further, this (A) is reacted with amines (B) at 0 to 140 ° C. to obtain a urea-modified polyester.

  When reacting (PIC) and when reacting (A) and (B), a solvent may be used if necessary. Usable solvents include aromatic solvents (toluene, xylene, etc.); ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.); esters (ethyl acetate, etc.); amides (dimethylformamide, dimethylacetamide, etc.) and ethers And those inert to isocyanates (PIC) such as tetrahydrofuran (such as tetrahydrofuran).

  In addition, in the crosslinking and / or extension reaction between the polyester prepolymer (A) and the amines (B), a reaction terminator can be used as necessary to adjust the molecular weight of the resulting urea-modified polyester. Examples of the reaction terminator include monoamines (diethylamine, dibutylamine, butylamine, laurylamine, etc.), and those obtained by blocking them (ketimine compounds).

  The weight average molecular weight of the urea-modified polyester is usually 10,000 or more, preferably 20,000 to 10,000,000, and more preferably 30,000 to 1,000,000. If it is less than 10,000, the hot offset resistance deteriorates. The number average molecular weight of the urea-modified polyester or the like is not particularly limited when the above-mentioned unmodified polyester is used, and may be a number average molecular weight that can be easily obtained to obtain the weight average molecular weight. When the urea-modified polyester is used alone, its number average molecular weight is usually 2000-15000, preferably 2000-10000, more preferably 2000-8000. When it exceeds 20000, the low-temperature fixability and the glossiness when used in a full-color apparatus are deteriorated.

  By using the unmodified polyester and the urea-modified polyester in combination, the low-temperature fixability and the gloss when used in the full-color image forming apparatus 100 are improved. Therefore, it is preferable to use the urea-modified polyester alone. The unmodified polyester may include a polyester modified with a chemical bond other than a urea bond.

  The unmodified polyester and the urea-modified polyester are preferably at least partially compatible with each other in terms of low-temperature fixability and hot offset resistance. Therefore, it is preferable that the unmodified polyester and the urea-modified polyester have a similar composition.

  The weight ratio of unmodified polyester to urea-modified polyester is usually 20/80 to 95/5, preferably 70/30 to 95/5, more preferably 75/25 to 95/5, and particularly preferably 80 /. 20-93 / 7. When the weight ratio of the urea-modified polyester is less than 5%, the hot offset resistance is deteriorated, and it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability.

  The glass transition point (Tg) of the binder resin containing unmodified polyester and urea-modified polyester is usually 45 to 65 ° C, preferably 45 to 60 ° C. If it is less than 45 ° C., the heat resistance of the toner deteriorates, and if it exceeds 65 ° C., the low-temperature fixability becomes insufficient. In addition, since the urea-modified polyester is likely to be present on the surface of the obtained toner base particles, the heat-resistant storage stability tends to be good even when the glass transition point is low as compared with known polyester-based toners.

(Coloring agent)
As the colorant, all known dyes and pigments can be used. For example, carbon black, nigrosine dye, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium yellow, yellow iron oxide, ocher , Yellow lead, titanium yellow, polyazo yellow, oil yellow, Hansa yellow (GR, A, RN, R), pigment yellow L, benzidine yellow (G, GR), permanent yellow (NCG), Vulcan fast yellow (5G, R), Tartrazine Lake, Quinoline Yellow Lake, Anthrazan Yellow BGL, Isoindolinone Yellow, Bengala, Red Dan, Lead Zhu, Cadmium Red, Cadmium Mercury Red, Antimon Zhu, Permanent Red 4R, Para Red, Phi Sayred, Parachlor Ortonito Aniline Red, Resol Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carmin Min BS, Permanent Red (F2R, F4R, FRL, FRLL, F4RH), Fast Scarlet VD, Belkan Fast Rubin B, Brilliant Scarlet G, Resol Rubin GX, Permanent Red F5R , Brilliant Carmine 6B, Pigment Scarlet 3B, Bordeaux 5B, Toluidine Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Medium, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake, Thio Indigo Red B, Thioindigo Maroon, Oil Red, Quinacridone Red, Pyrazolone Red Polyazo Red, Chrome Vermillion, Benzidine Orange, Perinone Orange, Oil Orange, Cobalt Blue, Cerulean Blue, Alkaline Blue Lake, Peacock Blue Lake, Victoria Blue Lake, Metal Free Phthalocyanine Blue, Phthalocyanine Blue, Fast Sky Blue, Indanthrene Blue (RS, BC), indigo, ultramarine blue, bitumen, anthraquinone blue, fast violet B, methyl violet, cobalt purple, manganese purple, dioxane violet, anthraquinone violet, chrome green, zinc green, chromium oxide, pyridian, emerald green, Pigment Green B, Naphthol Green B, Green Gold, Acid Green Lake, Malachite Green Lake, Phthalo Cyanine green, anthraquinone green, titanium oxide, zinc white, litbon and mixtures thereof can be used. The content of the colorant is usually 1 to 15% by weight, preferably 3 to 10% by weight, based on the toner.

  The colorant can also be used as a master batch combined with a resin. As a binder resin to be kneaded together with the production of the master batch or the master batch, a polymer of styrene such as polystyrene, poly-p-chlorostyrene, polyvinyl toluene or the like, or a copolymer of these and a vinyl compound, Polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, epoxy resin, epoxy polyol resin, polyurethane, polyamide, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, fat Aromatic or alicyclic hydrocarbon resins, aromatic petroleum resins, chlorinated paraffins, paraffin waxes and the like can be mentioned, and these can be used alone or in combination.

(Charge control agent)
Known charge control agents can be used, such as nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine dyes, alkoxy amines, quaternary ammonium salts (fluorine-modified 4 Secondary ammonium salts or compounds, tungsten simple substances or compounds, fluorine activators, salicylic acid metal salts, and metal salts of salicylic acid derivatives.

  Specifically, Bontron 03 of a nigrosine dye, Bontron P-51 of a quaternary ammonium salt, Bontron S-34 of a metal-containing azo dye, E-82 of an oxynaphthoic acid metal complex, E-84 of a salicylic acid metal complex , Phenolic condensate E-89 (above, Orient Chemical Industries, Ltd.), quaternary ammonium salt molybdenum complex TP-302, TP-415 (above, Hodogaya Chemical Co., Ltd.), quaternary ammonium salt copy Charge PSY VP2038, copy blue PR of triphenylmethane derivative, copy charge of quaternary ammonium salt NEG VP2036, copy charge NX VP434 (manufactured by Hoechst), LRA-901, LR-147 which is a boron complex (Nippon Carlit) Manufactured), copper phthalocyanine, perylene, quinacridone, azo And pigments and other high molecular compounds having functional groups such as sulfonic acid groups, carboxyl groups, and quaternary ammonium salts. Of these, substances that control the negative polarity of the toner are particularly preferably used.

  The amount of charge control agent used is determined by the type of binder resin, the presence or absence of additives used as necessary, and the toner production method including the dispersion method, and is not uniquely limited. Preferably, it is used in the range of 0.1 to 10 parts by weight with respect to 100 parts by weight of the binder resin. The range of 0.2 to 5 parts by weight is preferable. When the amount exceeds 10 parts by weight, the chargeability of the toner is too high, the effect of the charge control agent is reduced, the electrostatic attraction with the developing roller is increased, the developer fluidity is lowered, and the image density is lowered. Invite.

(Release agent)
As a release agent, a low melting point wax having a melting point of 50 to 120 ° C. works more effectively as a release agent in the dispersion with the binder resin between the fixing roller and the toner interface. The effect on high temperature offset is exhibited without applying a release agent such as oil. Examples of such a wax component include the following. Waxes and waxes include plant waxes such as carnauba wax, cotton wax, wood wax and rice wax, animal waxes such as beeswax and lanolin, mineral waxes such as ozokerite and cercin, and paraffin and microcrystalline. And petroleum waxes such as petrolatum.

  In addition to these natural waxes, synthetic hydrocarbon waxes such as Fischer-Tropsch wax and polyethylene wax, and synthetic waxes such as esters, ketones, and ethers can be used. Furthermore, fatty acid amides such as 12-hydroxystearic acid amide, stearic acid amide, phthalic anhydride imide, chlorinated hydrocarbon, and low molecular weight crystalline polymer resin, poly-n-stearyl methacrylate, poly-n- A crystalline polymer having a long alkyl group in the side chain such as a homopolymer or copolymer of polyacrylate such as lauryl methacrylate (for example, a copolymer of n-stearyl acrylate-ethyl methacrylate, etc.) can also be used. . The charge control agent and the release agent can be melt-kneaded together with the master batch and the binder resin, and of course, they may be added when dissolved and dispersed in the organic solvent.

(External additive)
Inorganic fine particles are preferably used as an external additive for assisting the fluidity, developability and chargeability of the toner particles. The primary particle diameter of the inorganic fine particles is preferably 5 × 10 ^-3 ~2μm, it is particularly preferably 5 × 10 ^-3 ~0.5μm. Moreover, it is preferable that the specific surface area by BET method is 20-500 m < ² > / g. The use ratio of the inorganic fine particles is preferably 0.01 to 5 wt% of the toner, and particularly preferably 0.01 to 2.0 wt%.

  Specific examples of the inorganic fine particles include, for example, silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, tin oxide, quartz sand, clay, mica, wollastonite, diatomaceous earth. Examples include soil, chromium oxide, cerium oxide, bengara, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, and silicon nitride.

  Among these, as the fluidity imparting agent, it is preferable to use hydrophobic silica fine particles and hydrophobic titanium oxide fine particles in combination. In particular, when stirring and mixing are performed using particles having an average particle size of 5 × 10-2 μm or less, the electrostatic force and van der Waals force with the toner are remarkably improved. Even when stirring and mixing inside the developing device is performed, a fluidity-imparting agent is not detached from the toner, a good image quality that does not cause fireflies and the like is obtained, and a reduction in residual toner is further achieved. .

  Titanium oxide fine particles are excellent in environmental stability and image density stability, but have a tendency to deteriorate the charge rise characteristics. Therefore, if the amount of titanium oxide fine particles added is larger than the amount of silica fine particles added, this side effect is affected. It can be considered large. However, when the added amount of the hydrophobic silica fine particles and the hydrophobic titanium oxide fine particles is in the range of 0.3 to 1.5 wt%, the charge rising characteristics are not greatly impaired, and the desired charge rising characteristics can be obtained, that is, repeated copying. Stable image quality can be obtained even if

  Next, a toner manufacturing method will be described. Here, although a preferable manufacturing method is shown, the present invention is not limited to this.

(Toner production method)
1) A toner material solution is prepared by dispersing a colorant, unmodified polyester, a polyester prepolymer having an isocyanate group, and a release agent in an organic solvent.
The organic solvent is preferably volatile with a boiling point of less than 100 ° C. from the viewpoint of easy removal after toner base particle formation. Specifically, toluene, xylene, benzene, carbon tetrachloride, methylene chloride, 1,2-dichloroethane, 1,1,2-trichloroethane, trichloroethylene, chloroform, monochlorobenzene, dichloroethylidene, methyl acetate, ethyl acetate, methyl ethyl ketone, Methyl isobutyl ketone and the like can be used alone or in combination of two or more.

  In particular, aromatic solvents such as toluene and xylene and halogenated hydrocarbons such as methylene chloride, 1,2-dichloroethane, chloroform, and carbon tetrachloride are preferable. The usage-amount of an organic solvent is 0-300 weight part normally with respect to 100 weight part of polyester prepolymers, Preferably it is 0-100 weight part, More preferably, it is 25-70 weight part.

2) The toner material liquid is emulsified in an aqueous medium in the presence of a surfactant and resin fine particles.
The aqueous medium may be water alone or an organic solvent such as alcohol (methanol, isopropyl alcohol, ethylene glycol, etc.), dimethylformamide, tetrahydrofuran, cellosolves (methyl cellosolve, etc.), lower ketones (acetone, methyl ethyl ketone, etc.). It may be included.

  The amount of the aqueous medium used relative to 100 parts by weight of the toner material liquid is usually 50 to 2000 parts by weight, preferably 100 to 1000 parts by weight. If the amount is less than 50 parts by weight, the dispersion state of the toner material liquid is poor, and toner particles having a predetermined particle diameter cannot be obtained. If it exceeds 20000 parts by weight, it is not economical. Further, in order to improve the dispersion in the aqueous medium, a dispersant such as a surfactant and resin fine particles is appropriately added.

  As surfactants, anionic surfactants such as alkylbenzene sulfonates, α-olefin sulfonates, phosphate esters, alkylamine salts, amino alcohol fatty acid derivatives, polyamine fatty acid derivatives, amine salt types such as imidazoline, Quaternary ammonium salt type cationic surfactants such as alkyltrimethylammonium salt, dialkyldimethylammonium salt, alkyldimethylbenzylammonium salt, pyridinium salt, alkylisoquinolinium salt, benzethonium chloride, fatty acid amide derivative, polyhydric alcohol Nonionic surfactants such as derivatives, for example, amphoteric surfactants such as alanine, dodecyldi (aminoethyl) glycine, di (octylaminoethyl) glycine and N-alkyl-N, N-dimethylammonium betaine And the like.

Further, by using a surfactant having a fluoroalkyl group, the effect can be obtained in a very small amount. Examples of the anionic surfactant having a fluoroalkyl group that is preferably used include fluoroalkyl carboxylic acids having 2 to 10 carbon atoms and metal salts thereof, disodium perfluorooctanesulfonyl glutamate, 3- [ω-fluoroalkyl (C _6- C ₁₁ ) oxy] -1-alkyl (C ₃ -C ₄ ) sodium sulfonate, 3- [ω-fluoroalkanoyl (C ₆ -C ₈ ) -N-ethylamino] -1-propanesulfonic acid sodium, fluoroalkyl (C ₁₁ ~C ₂₀₎ carboxylic acids and metal salts thereof, perfluoroalkyl carboxylic acids (C ₇ ~C ₁₃₎ and metal salts thereof, perfluoroalkyl (C ₄ ~C ₁₂₎ sulfonic acids and metal salts thereof, perfluorooctane Sulfonic acid diethanolamide, N-propyl-N- (2-hydroxyethyl) perfluoroo Tan sulfonamide, perfluoroalkyl (C ₆ ~C ₁₀₎ sulfonamide propyl trimethyl ammonium salts, perfluoroalkyl (C ₆ ~C ₁₀₎ -N- ethylsulfonyl glycine salts, monoperfluoroalkyl (C ₆ ~C ₁₆₎ Examples thereof include ethyl phosphate.

  Product names include Surflon S-111, S-112, S-113 (Asahi Glass Co., Ltd.), Florard FC-93, FC-95, FC-98, FC-129 (Sumitomo 3M Co., Ltd.), Unidyne DS-101. DS-102 (manufactured by Daikin Industries, Ltd.), Megafac F-110, F-120, F-113, F-191, F-812, F-833 (manufactured by Dainippon Ink, Inc.), Xtop EF-102, 103, 104, 105, 112, 123A, 123B, 306A, 501, 201, 204 (manufactured by Tochem Products), and Fgentent F-100, F150 (manufactured by Neos).

  Moreover, as the cationic surfactant, aliphatic quaternary ammonium such as aliphatic primary, secondary or secondary amic acid, perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salt which has a right fluoroalkyl group is used. Salt, benzalkonium salt, benzethonium chloride, pyridinium salt, imidazolinium salt, trade names include Surflon S-121 (manufactured by Asahi Glass), Florard FC-135 (manufactured by Sumitomo 3M), Unidyne DS-202 (Daikin Industries) Smoke), Megafac F-150, F-824 (Dainippon Ink Co., Ltd.), Xtop EF-132 (Tochem Products), Footage F-300 (Neos), and the like.

  The resin fine particles are added to stabilize the toner base particles formed in the aqueous medium. For this reason, it is preferable to add so that the coverage existing on the surface of the toner base particles is in the range of 10 to 90%. For example, polymethyl methacrylate fine particles 1 μm and 3 μm, polystyrene fine particles 0.5 μm and 2 μm, poly (styrene-acrylonitrile) fine particles 1 μm, trade names are PB-200H (manufactured by Kao Corporation), SGP (manufactured by Soken Co., Ltd.), Techno Examples thereof include polymer SB (manufactured by Sekisui Chemical Co., Ltd.), SGP-3G (manufactured by Sokensha), and micropearl (manufactured by Sekisui Fine Chemical Co., Ltd.). In addition, inorganic compound dispersants such as tricalcium phosphate, calcium carbonate, titanium oxide, colloidal silica, and hydroxyapatite can also be used.

  As a dispersant that can be used in combination with the above resin fine particles and inorganic compound dispersant, the dispersed droplets may be stabilized by a polymer protective colloid. For example, acrylic acid, methacrylic acid, α-cyanoacrylic acid, α-cyanomethacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid or maleic anhydride and other (meth) acrylic monomers containing hydroxyl groups Bodies such as acrylic acid-β-hydroxyethyl, methacrylic acid-β-hydroxyethyl, acrylic acid-β-hydroxypropyl, methacrylic acid-β-hydroxypropyl, acrylic acid-γ-hydroxypropyl, methacrylic acid-γ-hydroxy Propyl, acrylic acid-3-chloro-2-hydroxypropyl, methacrylic acid-3-chloro-2-hydroxypropyl, diethylene glycol monoacrylate, diethylene glycol monomethacrylate, glycerol monoacrylate, glycerol monomethacrylate Luric acid esters, N-methylol acrylamide, N-methylol methacrylamide, etc., vinyl alcohol or ethers with vinyl alcohol, such as vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, or compounds containing vinyl alcohol and a carboxyl group Esters such as vinyl acetate, vinyl propionate, vinyl butyrate, acrylamide, methacrylamide, diacetone acrylamide or their methylol compounds, acid chlorides such as acrylic acid chloride, methacrylic acid chloride, vinyl pyridine, vinyl pyrrolidone, vinyl Nitrogen compounds such as imidazole and ethyleneimine, or homopolymers or copolymers such as those having a heterocyclic ring thereof, polyoxyethylene, poly Xoxypropylene, polyoxyethylene alkylamine, polyoxypropylene alkylamine, polyoxyethylene alkylamide, polyoxypropylene alkylamide, polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl phenyl ether, polyoxyethylene stearyl phenyl ester, polyoxy Polyoxyethylenes such as ethylene nonylphenyl ester, celluloses such as methyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose can be used.

  The dispersion method is not particularly limited, and known equipment such as a low-speed shear method, a high-speed shear method, a friction method, a high-pressure jet method, and an ultrasonic wave can be applied. Among these, the high-speed shearing method is preferable in order to make the particle size of the dispersion 2 to 20 μm. When a high-speed shearing disperser is used, the rotational speed is not particularly limited, but is usually 1000 to 30000 rpm, preferably 5000 to 20000 rpm. The dispersion time is not particularly limited, but in the case of a batch method, it is usually 0.1 to 5 minutes. The temperature during dispersion is usually 0 to 150 ° C. (under pressure), preferably 40 to 98 ° C.

3) At the same time as the preparation of the emulsion, the amines (B) are added to cause a reaction with the polyester prepolymer (A) having an isocyanate group.
This reaction involves molecular chain crosslinking and / or elongation. The reaction time is selected depending on the reactivity between the isocyanate group structure of the polyester prepolymer (A) and the amines (B), but is usually 10 minutes to 40 hours, preferably 2 to 24 hours. The reaction temperature is generally 0 to 150 ° C, preferably 40 to 98 ° C. Moreover, a well-known catalyst can be used as needed. Specific examples include organotin catalysts such as dibutyltin laurate and dioctyltin laurate.

4) After completion of the reaction, the organic solvent is removed from the emulsified dispersion (reactant), washed and dried to obtain toner base particles.
In order to remove the organic solvent, the temperature of the entire system is gradually raised in a laminar stirring state, and after giving strong stirring in a certain temperature range, the solvent base is removed to produce spindle-shaped toner base particles. . Further, when an acid such as calcium phosphate salt or an alkali-soluble material is used as the dispersion stabilizer, the calcium phosphate salt is dissolved from the toner base particles by a method such as dissolving the calcium phosphate salt with an acid such as hydrochloric acid and washing with water. Remove. It can also be removed by operations such as enzymatic degradation.

5) A charge control agent is injected into the toner base particles obtained above, and then inorganic fine particles such as silica fine particles and titanium oxide fine particles are externally added to obtain a toner.
The injection of the charge control agent and the external addition of the inorganic fine particles are performed by a known method using a mixer or the like. Thereby, a toner having a small particle size and a sharp particle size distribution can be easily obtained. Furthermore, by giving strong agitation in the process of removing the organic solvent, the shape between the true spherical shape and the rugby ball shape can be controlled, and the surface morphology is also controlled between the smooth shape and the umeboshi shape. be able to.

  When the above method is used, a shape close to a sphere can be obtained as compared with the pulverized toner. Therefore, the granularity is improved, and a high-quality image without roughness can be obtained. Further, it is easy to reduce the particle size, and it is effective for higher image quality. On the other hand, since unevenness is also manifested, by combining with the present invention, a developing device with high image quality and less density unevenness can be provided.

  The toner has a volume average particle diameter of 3 to 8 μm and a ratio (Dv / Dn) of the volume average particle diameter (Dv) to the number average particle diameter (Dn) in the range of 1.00 to 1.40. Preferably there is. In order to reproduce minute dots of 600 dpi or more, the toner preferably has a volume average particle diameter of 3 to 8 μm. The ratio (Dv / Dn) of the volume average particle diameter (Dv) to the number average particle diameter (Dn) is preferably in the range of 1.00 to 1.40. The closer (Dv / Dn) is to 1.00, the sharper the particle size distribution.

  With such a toner having a small particle size and a narrow particle size distribution, the toner charge amount distribution is uniform, a high-quality image with little background fogging can be obtained, and the electrostatic transfer method has a high transfer rate. can do. By combining with the present invention, a developing device with high image quality and less density unevenness can be provided. The toner shape factor SF-1 is preferably in the range of 100 to 180, and the shape factor SF-2 is preferably in the range of 100 to 180.

  6A and 6B are diagrams schematically illustrating the shape of the toner in order to explain the shape factor SF-1 and the shape factor SF-2. The shape factor SF-1 indicates the ratio of the roundness of the toner shape and is represented by the following formula (1). This is a value obtained by dividing the square of the maximum length MXLNG of the shape formed by projecting the toner on a two-dimensional plane by the figure area AREA and multiplying by 100π / 4.

SF-1 = {(MXLNG) ² / AREA} × (100π / 4) (1)
When the value of SF-1 is 100, the shape of the toner is a true sphere, and becomes larger as the value of SF-1 increases.

  The shape factor SF-2 indicates the ratio of the unevenness of the toner shape, and is represented by the following formula (2). A value obtained by dividing the square of the perimeter PERI of the figure formed by projecting the toner on the two-dimensional plane by the figure area AREA and multiplying by 100π / 4.

SF-2 = {(PERI) ² / AREA} × (100π / 4) Expression (2)
When the value of SF-2 is 100, the unevenness does not exist on the toner surface, and the unevenness of the toner surface becomes more remarkable as the value of SF-2 increases. Specifically, the shape factor is measured by taking a photograph of the toner with a scanning electron microscope (S-800: manufactured by Hitachi, Ltd.), introducing it into an image analyzer (LUSEX 3: manufactured by Nireco) and analyzing it. Calculated.

  When the shape of the toner is close to a sphere, the contact state between the toner and the toner or the toner and the photosensitive member becomes a point contact, so that the adsorbing force between the toners becomes weak and the fluidity becomes high. In addition, the attractive force between the toner and the photoreceptor is weakened, and the transfer rate is increased. If either of the shape factors SF-1 and SF-2 exceeds 180, the transfer rate is lowered, which is not preferable. A high transfer rate faithfully reproduces the developed toner image. That is, if there is development unevenness in the developed toner image, it is faithfully reproduced without blurring after transfer. Therefore, there is a risk that development unevenness may become apparent, and when combined with the present invention, a developing device with high image quality and less development unevenness can be provided.

  The shape of the toner used in the developing device and the image forming apparatus according to the embodiment of the present invention is substantially spherical, and can be represented by the following shape definition. FIG. 7A is a diagram schematically showing the shape of the toner according to the embodiment of the present invention. In FIG. 7A, when a substantially spherical toner is defined by a major axis r1, a minor axis r2, and a thickness r3 (where r1 ≧ r2 ≧ r3), the toner according to the present embodiment is a long toner. The ratio of axis to minor axis (r2 / r1) (see FIG. 7B) is 0.5 to 1.0, and the ratio of thickness to minor axis (r3 / r2) (see FIG. 7C). Is preferably in the range of 0.7 to 1.0.

  When the ratio of the major axis to the minor axis (r2 / r1) is less than 0.5, the dot reproducibility and transfer efficiency are inferior because of being away from the true spherical shape, and high-quality image quality cannot be obtained. On the other hand, if the ratio of thickness to minor axis (r3 / r2) is less than 0.7, the shape is close to a flat shape, and a high transfer rate like a spherical toner cannot be obtained. In particular, when the ratio of the thickness to the minor axis (r3 / r2) is 1.0, the rotating body has a major axis as a rotation axis, and the fluidity of the toner can be improved. In addition, r1, r2, r3 can be measured by the following method, for example.

  That is, the toner is uniformly dispersed and adhered on a smooth measurement surface, and 100 particles of the toner are magnified 500 times by a color laser microscope “VK-8500” (manufactured by Keyence Corporation) to obtain the 100 toners. The major axis r1 (μm), the minor axis r2 (μm), and the thickness r3 (μm) of the particles can be measured and obtained from their arithmetic average values. The effect of the combination with the present invention is the same as that of the seventh aspect.

  The image forming apparatus according to the embodiment of the present invention uses the developing device. That is, the image forming apparatus according to the present embodiment includes an image carrier that carries an electrostatic latent image, a charging device that charges the image carrier, a developer carried on the developer carrier, and the image carrier. A developing device that is transported to an opposing development area and develops the latent image on the image carrier to form a toner image, a transfer device that transfers the developed toner image to a transfer material, and the image carrier after the transfer An image forming apparatus having a cleaning device for removing transfer residual toner remaining thereon, wherein the developing device of the present invention is used as the developing device.

  As the developing device of the image forming apparatus as shown in FIG. 1 described at the beginning, the first agitating and conveying means is located above the first agitating and conveying means and at a position in contact with the developer carried and moved on the developer carrier. By using the developing device of the present invention provided with the developer surface height adjusting member that increases the height of the developer surface above the one agitation and conveyance means, the unevenness in pumping (pitch unevenness) of the developer by the agitation and conveyance means is uniform. In addition, it is possible to provide a developing device capable of forming a highly reliable image in which developer agitation becomes strong and a pitch unevenness image does not occur.

  Furthermore, the process cartridge according to the embodiment of the present invention uses the developing device. That is, the process cartridge according to the present embodiment is a process cartridge that integrally supports the image carrier and at least the developing device and is detachable from the image forming apparatus main body. A developing device is used.

  For example, a process cartridge in which a charging unit 105, a developing unit 106, a photosensitive member 107, and a cleaning unit 108 as shown in FIG. 8 are integrated, and the developing device of the present invention described above is used as the developing unit 106. . Since the developer surface height adjustment member is provided at a position in contact with the developer moving on the developer carrying member of the developing device, it is difficult to pump up the developer by the agitating and conveying means (pitch unevenness). A leveling (smoothing) effect by the height adjusting member and a strong stirring of the developer at the height adjusting unit can provide a highly reliable process cartridge that does not generate a pitch unevenness image.

  Although the present invention has been specifically described above based on the preferred embodiments, it is needless to say that the present invention is not limited to the above-described ones and can be variously modified without departing from the gist thereof.

1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an embodiment of the present invention. 1 is a schematic configuration diagram illustrating an example of a developing device according to an embodiment of the present invention. 1 is a schematic configuration diagram illustrating an example of a developing device according to an embodiment of the present invention. It is a figure which shows the stirring conveyance means of the developing device which concerns on embodiment of this invention, and the agent surface height adjustment member of a developer. It is sectional drawing which shows typically the structure of the carrier which concerns on embodiment of this invention. FIG. 4 is a diagram schematically illustrating a toner shape for explaining a shape factor of the toner according to the exemplary embodiment of the present invention. FIG. 3 is a diagram schematically illustrating the shape of a toner in order to explain a major axis, a minor axis, and a thickness of the toner according to an embodiment of the present invention. It is a schematic structure figure showing an example of a process cartridge concerning an embodiment of the present invention.

Explanation of symbols

2Y image carrier 40Y developing device 42Y developing roller (or developer carrier)
43Y first conveying screw (or first agitating and conveying means)
44Y Second conveying screw (or second agitating and conveying means)
45Y regulating blade (or regulating member)
50Y developer surface height adjusting member 50aY closest portion of developer surface height adjusting member to developer carrying member 55Y developer reflux portion 500 carrier 501 ferrite 502 coat film 503 alumina particles

Claims (10)

A developing device having a developer carrying member, a regulating member that regulates the thickness of the developer on the developer carrying member, a first stirring and conveying unit that conveys the developer while stirring, and a second stirring and conveying unit Because
A developer surface height adjusting member that adjusts the height of the developer is provided above the first agitating and conveying means and at a position in contact with the developer carried and moved on the developer carrier. A developing device.   The cross-sectional shape of the developer surface height adjusting member is L-shaped, and the height is temporarily reduced from the upstream side to the downstream side of the first stirring and conveying means. 2. The developing device according to 1.   The developing device according to claim 1, wherein the developer is a two-component developer including a toner and a magnetic carrier, and the particle size of the magnetic carrier is 20 to 50 μm.   The magnetic carrier is characterized in that a magnetic core material is coated with a resin coat film, and the resin coat film contains a resin component obtained by crosslinking a thermoplastic resin and a melamine resin, and a charge control agent. The developing device according to claim 3.   In the toner, a toner material liquid in which at least a polyester prepolymer having a functional group containing a nitrogen atom, polyester, a colorant, and a release agent is dispersed in an organic solvent is subjected to a crosslinking reaction or an extension reaction in an aqueous medium. 5. The developing device according to claim 3, wherein the developing device is a toner obtained by causing at least one reaction.   The toner has a volume average particle diameter of 3 to 8 μm and a ratio (Dv / Dn) of the volume average particle diameter (Dv) to the number average particle diameter (Dn) is in the range of 1.00 to 1.40. The developing device according to claim 5.   The developing device according to claim 5 or 6, wherein the toner has a shape factor SF-1 in the range of 100 to 180 and a shape factor SF-2 in the range of 100 to 180.   The toner has a substantially spherical shape, and the shape is defined by a major axis r1, a minor axis r2, and a thickness r3 (provided that r1 ≧ r2 ≧ r3), and the ratio of the major axis r1 to the minor axis r2 ( r2 / r1) is in the range of 0.5 to 1.0, and the ratio (r3 / r2) of the thickness r3 to the minor axis r2 is in the range of 0.7 to 1.0. Item 8. The developing device according to any one of Items 5 to 7. An image carrier, a charging unit for charging the image carrier, a transfer unit for transferring a toner image to a transfer material, a cleaning unit for removing transfer residual toner remaining on the image carrier after the transfer, and development An image forming apparatus comprising: a developing device that carries a developer on a developer carrying member, transports the developer to a developing region facing the image carrying member, and develops a latent image on the image carrying member to form a toner image. And
The image forming apparatus according to claim 1, wherein the developing device is the developing device according to claim 1. An image carrier, and a developing device that carries at least a developer on the developer carrier, transports the developer to a development region facing the image carrier, and develops a latent image on the image carrier to form a toner image. And a process cartridge that is detachably attached to the image forming apparatus main body,
The process cartridge according to claim 1, wherein the developing device is the developing device according to claim 1.

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